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0.1. VicCARTHY.

SIGNAL. APPucA'TvloN FILED' AuG.8, Isls.

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Patented Aug. 15, 1916.

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APPUcAnoNfmED AUG.8.1913.

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ENVENTE? D. J. MCCARTHY.

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Lanarte.

T0 all whom t may concern: n

Be it known that l?. DANIEL J. MGCARTHY, a citizen of the United States, residing at Wilkinsburg, in thecounty of Allegheny and State of Pennsylvania, have invented certainonew and useful Improvements in Signals; of which the following is a 'specification.

My invention relates to signals, and par- Speeilcation.` of Letters Patent.

Patenten nog. aa, tere.

l.Application l'ed August, 1913. v- Serial No. 783,719.

surface non-redective and including one arrangement of opaque screens embodying my invention. Fig. 12 is ,a view showing in front elevation the signal .shown in Fig. 11.

'Fig. 13' iS a view Showingv in longitudinal ticularly to Signals of the type in which rays from 'a Source of light are-projected in a beam byl suitable optical devices.

Signals embodying my invention are especially well adapted for use in connection with railway signaling.

Une object ot my invention is to prevent the signal being falsely caused to appear illuminated by rays from anI outside source 'of light entering the signal and being pro'- jected back by the vices.

1 will describe several forms of signals optical device or deembodying my invention, and will then point out the novel Jfeatures thereof in embodyin my invention and having still' another arrangement lof opaque screens. Fig. 6 is a view showing in front elevation the signal Shown in Fig. 5. Fig. 7 is a view showing in longitudinal section a signal embodying my 'invention and showing stillV a diiierent arrangement of o aque screens. Fig. 8 is a view showing in ront elevation the signal shown in Fig. 7.

tion and embodying still another form and arrangement 'of opaque screens. Fig. 10 is a view showing in front elevation thesignal shown in Fig. 9. Fig. 11 is a view showing in longitudinal Section a signal comprising a parabolic reflector having portions of lts Fig. 9 is a view Showing a signal embodymg my inven-` section another form of signal `,comprising a reflector formed of an innite number of zones of linfinitely small thickness and in-l cludingone arrangement of opaque screens embodylng my invention. Fig. 14* is a view showing 1n front elevation the signal shown 'in Fig. 13. Fig. 15 is a view showing ,in

longitudinal Section another form of signal comprising a reector formed of three zones having diderent focal points and including one form of opaque screens embodying my invention. Fig. 16 is a view showing in fr ont elevation the signal shown in Fig. 15. Fig. 17 is a view showing in longitudinal section another form of signal comprising a Mangin mirror and a lens and having one arrangement of opaque Screens'embodying my invention. Fig. i8 .is a view showing in -front elevation the signal shown in Fig. 17.

Similar reference characters refer to` similar parts in each of the several views."

Referring first toFig. 1, R designates' a reflector which, as here shown, ,isv in' the form of a paraboloid whose principal *axis is in the vline 0A, and whose focus is at point 10. 'Located adjacent the focus 10 is la source of lightwhich, as here shown, is. an incandescent electric lamp 11, having' a filament 12 which is concentratedaround .the focus 10. ,lt is well understood that all rays of light emanating from the focuskl() and striking the surface oat redector R are projected from the redector in lines substantially parallel tothe 'airis U-A., thus forming a beam of, light parallel to the axis When rays of light enter the reflector R from an outside source, such as from the s un or a locomotive headlight, vand when such rays are 4parallel to the axis U-A, each eov such ra which strikes the interior surface ofI the re ector is projected so that it passes through the focus. If the reiector were a complete paraboloid, and if its entire interior surface were reiiective, each of these' rays from the outsidesource would, after passing through the focal point 10, again strike the'surfaceof the reiector and be reiiected back in a line parallel to the axis `tgt-ne., so that these rays also would form a beam of light parallel to axis O-A; and when the lamp 11 is extinguished, this beam i might lcause the' signal to have the same appearance as though the lamp 11 were illuminated.'V In order to' avoid such false indication due to rays parallel to the axis O-A, the reliector R is cut away from the apex to a circle cut by a plane passing through a point 13 a short distance from the focuslO and'onthe opposite side of the focus from the apex. By means of this construction all rays of light from an exterior source which enter the reflector in lines axis O-A will pass throng the focus 10 illuminated. Such rays are indicate for example, by lines 30, 31, 32, 33, and 34.

In order to prevent falseindications due to rays of light from an outside source which A ranged, the common center being 1n the axisl v and located that, all, or nearly all, rays an outside source of light which` may enteryGli enter the reflector in lines not parallel 'to axis O-A, I provide one or more screens of opaque material -so located as to intercept thesel `rays. InFigs l I haveshown three screens 14, 14a and 14", eachin the form of a Ting, Which. rings are concent 'cally ar- A. Thesescreens maybe of any suitable opaque andthin material such as thin.

tin, and they may be mounted in the reflector 1n any suitable manner. Inasmuch as the rings are parallel to the axis O-A and are f thin,'they mtercept only a very few of the rays of light from the lamp 12 which are projected in the beam from the reflector. These rings, as here shown, are s o designed rom the reflector in lines not parallel to axis O,-'A are intercepted either before striking any point on the surface of the reflector or after striking one or more points on the surface and before being'again projected out of the large end of the reflector. For example, if a ray should enter ,the reflector in line 15 between screens 14 and 14a it would strike the reflecting surface at oint 16 from which it would be projected 1n a line .3 5 which strikes screen 14a atpoint 20 where the ray would be absorbed. Similarly, if a ray should enterthe reflector in line 17 between screens 14a and 14b it would strike the re fleeting surface at point 18 from which it would be projected in line 36, striking screen 14b at point 19 If a ray should enter the reiector in line 21,' it would strike the reliecting surface at point 22 from-which it would be projected to Apoint 23 then to point 24 and from there to point 25 from which it would ,be projected in a line which strikes screen 14b at point 26 where it would be absorbed. Obviously, certain rays which enter the reflector in lines nearly parallel to axis O-Avwill arallel to the shown,

,where it would be absorbed.

strike the reflecting surface and will pass out c at the opening in the rear of the refiector;

foreXaInple, a ray in line 27 vwould lstrike v the reflecting surface at point 28 from which'.A

it` wouldbe reflected in line 29 which does not pass through the focus 10, 'but which does pass out through the opening in the vproperly designed the signal cannot be caused to falsely appear illuminated by light entering-the signal f oni-an ,outside source Referring now to igs. 3 and 4, the signal ere shown comprises a paraboloidalreectorR whosefocus isatpoint 10. The sourceof light for this signal is 'an electric incandescent lainp l11a in which-is a screen 37 of opaque materialwhich, screen, as here is -a thin flat plate-which passes through thefocus 10. The filament of the lamplla is divided into two parts 12n and 12?, which the' screen .c 37 and which are concentrated as nearly as possible to the focal point'10.

It willlbe seen that this screen 37 willintercept all rays of light from an outside sourcewhich enter the reflector and which are rojected in lines which pass through .the ocus 10 or through points which lie inf the screen 37. For example," ray 38, which are located on. opposite sides of is .parallel to the axis'O-A o f the reflector,

strikes' the reflecting surface at 4point 39 and is projected in a line which asses through the focus 10, but this ray is Intercepted by the screen 37. Rays`40 and 41 are similarly intercepted by thecs'creen 37.A

In order'to intercept all rays which would not vbe intercepted by screen 37, I provide rings 14, 14", 14, and 14t of opaque :ma--

terial Which'are similar to the corresponding rings in Figs. 1 and 2. 42 strikes screen 14d and is absorbed thereby. .A ray. in line 43 enters 'the reflector betweenl screens 14l and v14 and strikes the reflecting surface at point 44 from which vit is projected to point 45 on screen 14 where it is absorbed. Similarly a ray in line 46 strikes the reflector Aat point 47 and is projected against the screen 14' at. point 48 where it is absorbed.

In the form of signal shown in Figs. 3 and 4 it might be possible that rays of light entering the reflector from an outside source in lines substantially parallel to the axis O-A could l out being-intercepted by this plate, and could, therefore, beagain projected out by the reflector.l For example, referring to Fig. 4, vray 49 might enter the reflector and strike the reilectmgsurface at a point-50 fromlwhich it'wou d be projected m a line which just misses the screen 37 and would. strike the reflecting surface again ata point i 51 from which it would be projected out of A ray inline pass nearto the plate' 37 withinceste the reflector in a line nearly parallel to the of radial strips extending on each side of the plane of the screen 37. I

Referring now to Figs. 5 and 6, the signal here shown is similar to thatshown in Figs. 3 and 4, except -that the lamp 11 contains two opaque `screens 37 and 37a arranged in planes forming angles of 90- with each other. The line of intersection of these screens is coincident with the axis O-A and therefore passes through the focus 10. The filament of lamp 11b is divided into four sections 12, 12d, 12", and 12" each of which sections is concentrated and is located as nearly as possible to the focus 10. The four sections of the filament are located respectively in the four quadrants formed by the screens 37 and 37, as clearly shown in Fig. 6. Ther two screens 37 and 37*l intercept all'rays of light from an outside source which enter the reflector in lines parallel or nearly parallel to axis- 0-A, hence with this arrangement of screens it is unnecessary to blacken any portion of the surface of the reflector R. The signal is provided with ringsV 14", 14d, 14, and llf of opaque material, as in Figs. 3 and Ll, to intercept all other rays which enter the reflectors from an outside source.

Referring now to Figs. 7 and 8,\`the signal here shown is similar to that shown in Figs. 5 and 6, except that instead of the opaque screens in the electric lamp, T have shown a lamp 11 Vof aV usual type, which lamp is surrounded by a cage comprising slats 56 of opaque material'alternating with open spaces, the slats being parallel with the axis O-A. The cage 55 is so designed that, considering the axis U-A as the center line, each point in an open space between slats is diametrically opposite to a point in a slat 56. This is clearly shown in Fig. '8.

It will be seen that with this construction any ray lof light fromr an outside source which enters the reflector in a line parallel to the axis O-A will be intercepted by a Slat 56 either just before reaching the focus j 10 or just after passing through this point.

.source which enter the reflector.

The signal is also provided with rings 14C,

1421419 and 14, as in the preceding-views,

to intercept all other rays from an outside Referring now to Figs. 9 and 10, the signal here shown comprises, as in the preceding views, a paraboloidal reflector R whose focus is at point 10. The source of light is an electric incandescent lamp 11 having a circularly arranged filament 12E which surrounds an opaque cylindrical member 57.

This member 57 is so located that the focus 10 `:is in substantially th'e center line of the member. It will be seen that any ray of lightv from an outside source which enters the reflector R in a line substantially parallel to the axis fl-,A will be intercepted by the cylindrical member 57 before reaching ithe focus 10, hence'such rays will not be again projected by the reector In the signal here shown l have illustrated another form of screen 58` for intercepting all other rays from an outside source, this screen being in the form of a spiral of thin opaque material. This spiral acts in the same manner as the rings 14, 14d, 14:2, 11F in the signals shown in the preceding views. 1t is understood that either the spiral or the concentric rings may be employed in any of the signals here shown.

Referring now to Figs. 11 and 12, the signal here shown comprises a reflector R Whose principal axis is in the line O-A and y Whose focus is at point 10. The source of arranged that any straight line zfrom any point in a reflective strip passing through the axis U- will strike a point in a nonre'flective strip. Hence it will be seen that any ray of light from 'an outside source which enters the reflector in such direction that it strikes a point on a reflective strip and is projected through the axis (l-A will strike a point on a non-reflective strip and will be absorbed. This applies to rays parallel to axis O-A, and also to other rays which are projected through the axis (l-l-l. To .intercept all other rays from `an outside source, T provide opaque rings 14, 14d, 14e and 14 as h'ereinbefore explained. The nonreective strips 59 are preferably slightly wider than the reflective strips, as shown 1n the drawing, to insure that all rays which strike a reflective strip near its edge and are projected through the axis O-A will then strike a `point on a blackened strip.

Referring-now to Figs. 13and 14, the

signal here shown comprises a reflector R2 formed of an infinite number of zones of a paraboloid, each zone being of infinitely small thickness, the foci of which zones lie in the axial line O-A between points GO focus of cach zone. With this construction,

each ray of light from an outside source which enters the reflector in a li'ne parallel to the axis 0-A Will be reflected from a point` on one Zone through the focus of that zone and ywill strike another zone from which it is projected in a line not parallel to axisn ()-A. To intercept these rays and prevent them leaving the reflector I provide opaque screens which, as here shown,

are concentric rings 62, 62il and 62b and are similar to the rings shown in the preceding views. For example, a ray 63 parallel to axis O-A strikes the reflector first at point 64, then at point 65 from Which it is projected in a line Whichstrikes ring 62b at point 66 and is absorbed. All, or nearly all,

rays from an outside source which are not O-A so that the foci of' the several zones are also located on this line." The zones are bounded by circlesa, of, a, athe planes of which are perpendicular to the axial line O-A. The focus of each zone lies outside of' the portion ofthe line O-A of the plane of circle a2. Located at and included between the planes of the boundary circles of the corresponding zone; that is, the focus of zone 67 is point 70, which is a short distance to the left of the plane vof circle a.. The focus of' zone 68 is at point 71, wh'ch a short distance to the left ofthe plane of circle a and the, focus of zone 69 is at point 72, which is to the left adjacent each focus 70, 71, and 72 is a source of light which, as here shown, is a filament of an incandescent lamp 11, the filament be-V l ing elongated and concentrated around the' foci in three coils 73, 74 and 75. Itis evident that with this construction all the rays of light from focus 70 `which strike zone 67 are yprojected in lines parallel to the axis O-A; for exa1nple,.ray X. Similarly, the rays from focus 71 which strike zone 68 are projected in lines parallel to axis O-A; f'or example, ray X. Similarly,'sthe rays from focus 72 which strike zone 69 are projected in lines parallel tovaxis O-A; for example, ray X3. All rays of light from an outside source which enter the reflector R3 in lines'pi'irallel to the axis O-A are either not reflected back through the large end of the reflector or are reflected back from a zone other than the zone which they strike upon entering the reflector, s'o that the rays which are thus reflected back through the large end arel no longer parallel to the axis O-A. The example,'ray Y strikes zone 67 and is projected 'through focus 70 and passes out throughl the back of the reflector in line Z. Ray Y2 strikes zone 68 and after` passing through the focus 71 of this zone Y strikes zone 67 from which it is projected in a line' Z2 Which is notl parallel to the axis,`

vONA. Similarly, ray Y3 strikes zone 69 and is projected through the 'focus 72 of this zone striking zone 68 from which it is projected in line Z3 Whichalso is not parallel to the axis O-A. In order to intercept Aall rays which enteifvthe reflector in lines' parallel to the axis O-A and are projected back through the large end of the reflector,

I provide an opaque screen 76, which is located in the path of all such rays. It Will be seen from the drawing that rays. Z2 and j Z3 are intercepted by this screen. As shown in Figs. `15 and 16 fthe screen 76 is' in the form of a single plane, but itis understood that` other forms of screens may be Aemi ployed, such, for example, as the concentric rings or the spiral screen shown-in. the pref ceding views.

Referring now to Figs.. 17 and 18, the

signal here shown comprises a Mangin mirror 77 whose focus is at p oint 10,-and-a lens 78 whose focus is at a point a considerable distance behind the mirror 77.' The source of light is an electric incandescent lamp 1l having a concentrated filament 12, the lamp being so located that the filament 12 is' betvveen the mirror 77 and ,the focus 10v so .that the rays of light from thcfilament 12 which strike the mirror 77 are projected in lines diverging somewhat from the axial lline O A. For example, ray 79 is projected from the mirror 77 in line 80. -The lens 78 is soconstructed and located that the rays thus projected from the mirror 77 after passing. through the lens 78 are projected in lines substantially parallel tothe axial line O-A, so -that these rays then form a beam of light composed of' substantially parallel rays. For example, Vthe `ray 80 after passing through the lens 78 is projectedin line 81'which isparallel to the axial line' O-A. lIn order to intercept all rays which enter the signal from an outside source of light, I provide rsuitable screens of opaque material, Which, as here shown, arg in the form of' conical rings 82, 82d and 82 source, after passing through ,the lens 78 is projected in line 84, and after striking theV mirror 77 is projected in line 85 which is again projected by the mirror 77 in line 86 and is then intercepted by ring 823. Similarly, all or nearly all rays from an outside source of light entering the signal through' the lens 78 are intercepted by one or another of the opaque screens' 82, 82, 82". The

opaque screens are so 4:formed that they 'are- For example, al ray 83 from an outside parallel with the rays which emanate from the filament 12 and are projected byffthe mirror 77 so that these screens o'erthe' least `possible obstruction to the rays projected from the lament 12.

` Signals embodying my invention are particularly adapted for use in railway` signaling. ,When so used, a. signal gives one indication when illuminated and 'another indicalWhen-a ,signal embodying my invention is tion `when extinguished. It Will be seen that used .in this manner and When its lamp is extinguished, itcannot be caused by light yfrom an outside source to falsely appear illumispirit and scope of my invention.

' optical means for SOllI'CG 111 il f 'a reflector for projecting rays from saidl Having thus described my invention, `What `Iclaimis: l f

1. A signal comprising a source of light, projecting rays from said source, and meansjfor preventing all rays which enter said signal from an outside source of-light from being projected back vby said optical means. j

2. A signal comprising a source of light, optical Ameans for projecting rays from said source, and opaque screens for preventing all rays which enter said signal from an outside source of light from being projected back by said optical means.

'3. Asignal comprising a source of light, optical means for vprojecting rays from said lines, and means for preventing all rays from an outside source of light which enter said signal at angles to said beam from being projected back by said opticalmeans.

.11. A signal comprising a source of light, a reflector for projecting raysfrom said source, and means for preventing all rays which enter said signal .from an outside source oflight from beingprojected back by the re- Hector.

5." A signal comprising a source of light, a `reflector for projecting rays from. said source, and opaque screens for preventing all lrays which enter said 'signal from an outside source of lightfrom being projected back by the reflector; .6. A signal comprising a source of light,

source in afbeanfr` of substantially yI )arallel lines, and rings of opaque material Ifor preventing all rays. from an. outside source of light which` enter said signal at angles to lines, means forms of signals em,x

beam of substantially parallelv said beam from being projected back by the reflector.

7. A signal comprising a source of light, a reflector for projecting rays from said source in a beam of substantially parallel for preventing all rays from an outside source which enter said signal in lines parallel to said beam from being projected back by the reflector, and means for preventing all rays from an outside source which enter said signal at angles to said beamfroin being projected back by the reflector.

`8. A signal comprising a source of light, a reflector for projecting rays from said source in a beam of substantially parallel lines, `and means for intercepting all rays from an outside source of light Which enter the reflector in lines" substantially parallel to said beam. o

9. A signal comprising a reflector having a focus, a source of light located adjacent the focus, and means located also adjacent said focus for interceptin'g all rays from an exterior source of light which enter said reflector and are projected in lines Which pass through said focus and points adjacent said focus. A

10. `A signal comprising a reflector having a focus, a source of light,located adjacent the focus, and means located also adjacent said focus for intercepting all rays from an exterior source of light which enter said refiector and are projected in lines which pass through said focus and points adjacent saidVA focus, and opaquey screens for; intercepting all other rays from an exterior source which enter the reflector.

11. A signal comprising a reflector-'having Y agfocus, an opaque screen passing through said focus for intercepting all rays of light from an outside source which yenter the re- Hector and are projected toward another pointy on the surface of the reflector, and sources of light located on opposite sides of said yscreen and adjacent-the focus.

i 12. A signal comprising a reflector having a, focus, an opaque screen passing through said focus for intercepting all rays of light from an outside source Which enter the re- Hector and are projected toward another pointon the surface of the reflector, sources of light located onopposite sides of said Screen vand adjacent the focus, and other opaque screens for intcrcepting all other rays from an outside source Whichenter the reflector.

In testimony whereof I afix my signature in presence of two Witnesses. f DANIEL J. MCCARTHY.

Witnesses:`

A. HERMAN WEGNER', R. L. Klsmn. 

